2018 MAZDA CX-9 Engine Problems

Here the facts, bought a car out of state (Illinois) from Iowa with 130,131 miles on Sept 12th 2025, Mazda CX9, the dealer did not disclose any problems with the car, after 3 months of ownership, the car overheats on highway whit family including a [XXX] infant, white smoke under the hood and exhaust pipe, towed home, radiator was replaced, few days after that a coolant leak, vehicle was sent to an authorized Mazda dealership for diagnose, the technician told us, according to Mazda procedures, a cod P111A, the vehicle's engine reached unsafe level of temperature and the whole engine needs to be replaced because a cracked head cylinder. This problem is well known by Mazda because they addressed on a TSB01-002/23 and CSP11 extended warranty, there is a flaw in the design of the engine near the cylinders manifold area, that cracks the engine and requires a full replacement...

Cracked cylinder head/leaking coolant.

. In January 2024, I purchased a used 2018 Mazda CX-9. The vehicle ran well until [XXX], when I discovered an engine coolant leak. My mechanic diagnosed it as a known defect involving the cylinder head. My husband contacted Mazda Customer Service (CS), and they advised us to get an official diagnosis from a Mazda dealer. We brought the car to Orland Park Mazda, where a diagnostic confirmed the defect (report attached). We later received an email from Mazda CS saying that since our car was at the dealership, Mazda would take the lead in submitting the goodwill repair claim (email attached). When we followed up with Orland Park Mazda, they informed us that no one from Mazda CS had contacted them to authorize the repair. We relayed this to Mazda CS and gave them the direct number of our service advisor, Adrian. Mazda CS said they would follow up...

Our Mazda CX-9, having roughly 86,000 miles, had catastrophic engine failure while driving. This is caused by coolant leaking at the cylinder head and around the exhaust manifold. This in turn caused a crack in the engine block. Mazda refused to fix this as it wasn’t a “recall” and only a tsb sent out. 1000 of people have reported this issue, causing failure while driving but Mazda will not recall the engines nor fix them under an extended warranty. After a 4 month battle with Mazda they refused to fix this in our car even though they know the engine is a bad manufacturing issue. A recall needs to be made and Mazda needs held accountable. Our exact cause was exactly what the TSB stated but Mazda stated our crack was not in the correct spot. They need a recall covering all engine block cracks due to faulty manufacturing

coolant leaking from engine block cracked cylinder head

Fan is not working and car is overheating when driving in traffic or low speeds - from forums this seems to be a common issue with this make/model and year

coolant leaks at the cylinder head around the exhaust manifold. Caused crack in the head. The Mazda 2.5t engine has this common issue that Mazda knows about. Mazda has a bulletin out but has not issued a recall. Car over heated and I was left stranded. Took car to mechanic who says I need to replace my entire engine.

My vehicle was low on antifreeze. I brought it into the dealer and had them look at it. They told me there was an antifreeze leak inside the engine. I told them, I think there's a service bulletin on it. TSB-01-013-21 And there are updates to it. They told me that the antifreeze leak does not pertain to this service bulletin. I told them, how can that be? When it's an antifreeze leak with an engine that only has 66000 miles on it so far. I spoke to mazda customer service in California They said the dealer is trying to get some financial relief for me to replace a $10000 engine. Which they said is on back order till march 2025. I said how can this leak not be a problem when the engine is on back order, I feel that this should not have happened With a engine, that...

I purchased a 2018 Mazda cx9 from a local used car dealer several weeks ago. Check engine light came on after a few weeks for cylinder 3 misfire and there was a steep decline of the vehicle performance (hard start, rough idle, lower mpg, sluggish driving). Took it to Berge Mazda who charged me for diagnostics/spark plugs, and ignition coil. They informed me the next steps were a compression tests, fuel injectors and if that didn’t fix the problem then they wanted to strip down the engine to evaluate the cylinder head. At this point I decided to take it to my local mechanic who I trust, he diagnosed a cracked cylinder head. Now I’m stuck with a car I just bought that’s unsafe to drive needing a 6-8k repair. Upon further research there is a widespread problem with Mazda’s manufacturing of there cylinder heads on certain models (including the...

- My 2018 Mazda CX 9 started stalling and jittering at idle and then eventually during slow driving. - Next day I got a check engine light, took to Mazda service center at the dealership I have been going to for last 6 years since I bought the car. - Service center diagnosed that there was a coolant leak through the cylinder head which seems to have cracked. - Further investigation indicated that this has been identified on many other similar Mazda engines and a Technical Service Bulletin had been issued by Mazda to Dealers. - On probing initially, dealership declined they were aware of any such problem. - The amount of repair for the engine replacement (cylinder head and other parts) is exuberant and is almost half of the value of my car, and is not expected for a low 44,000 miles car. - This had posed safety issue...

Engine cylinder head is leaking coolant. This is a known issue by Mazda as they have submitted a TSB on the issue but have yet to submit a recall. The leak causes overheating along with pollution of coolant fluid into the environment. The problem was diagnosed by a Mazda dealership. The leaking occurred before a light came on the dashboard. The light on the dashboard only came on once the engine began overheating.

Over heating /coolant leak

coolant leaks at cylinder head , Mazda of America knows issues but not willing to recall , they hava a bulletin number 01-002/23 . pls help

While driving on an interstate service drive in Michigan, my 2018 Mazda CX9 GT suddenly lost power and began flashing overheating warnings. I tried to move my vehicle to a safe spot while the warning and sudden loss of power was happening, which took a moment due to traffic flow and my family being in the car. I moved the car off the road, and let it cool. I slowly drove the car to a parts store to get coolant. Once the cooling system was filled, I brought the car home and began researching the problem. According to internet threads like Reddit this is a wide spread problem happening among Mazda vehicles with several law firms researching class action lawsuits. My car is stuck at the dealership until I can find $12,000 to fix it, and sadly there are hundreds more just like me according to sites like [XXX] and...

Approximately three weeks ago, a message on my dashboard said to pull over immediately. Your car is overheating. I pulled over to a nearby auto shop, which indicated that I was just low on coolant. They topped off the coolant, and everything appeared fine. Two weeks later, I got the same message on the dashboard, saying my car was overheating to pull over immediately. I pulled into a nearby auto parts store and purchased coolant for the vehicle. When I checked the reservoir, it was bone dry. I added coolant and drove the car home. The following day, I checked the reservoir to see if there was still coolant, but it was all gone. I scheduled an appointment with the Mazda dealer to have the car inspected. I also checked the Mazda Forum website to see if other vehicles of my make and model had similar issues since I had...

Vehicle had bucking coming to a stop. Noticed coolant was l9w, and temp guage was fluctuating at a stop slightly. Brought it to Lester Glenn mazda in toms river NJ, service writer informed us it is the cylinder head, and that the repair is approx $11,000. Vehicle only has 85000 miles on it, and was told by dealer that there is nothing they will do. This is a known issue, with a TSB issued in 2021 due to a defect in design where the turbo charger is mounted to the cylinder head. At this point, we are requesting the manufacturer take at least part of the responsibility of the poor design they sold to the open market, that is clearly a safety hazard to my wife and 4 kids, 1 of which is an infant.

Engine is leaking coolant apparently due to a cracked engine block caused by a manufacturing defect in the casting. Mazda has a Technical Service Bulletin, subject:Leaks at cylinder head and the number is 01-013/21. But they refuse to help cover their mistakes and now we owners are stuck with replacing an entire engine out of pocket. Shame on Mazda

Mine Mazda 2018 CX9 had coolant leakage at 55K miles. Issue is with faulty cylinder head acknowledged by Mazda in below mentioned TSB. I open up a case with Mazda (File Number XXX). Dealer quoted 7500$ expense and Mazda is providing assistance of 3101$. I have always serviced at Mazda authorized dealership and this issue was never reported. TSB [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My car started leaking coolant from cylinder, it is known issue for these models, unfortunately Mazda cooperation doesn’t cover the expenses, there is Service Bulletin about it, so basically so many car got affected or will affect from this problem. It is manufacturer fault, not about customer usage or mistake.

"High coolant temperature warning. Stop car at a safe place immediately " came up. Stopped car at a mechanic and diagnosed as coolant leak onto the engine.

Due to the flawed engine design which is well documented for these engines, ours started leaking coolant and it was eventually discovered that the head had cracked, and we were forced to have the head replaced. This repair cost us approximately $7600. Our hope is that Mazda will eventually issue a recall.

2018 CX9 with 74k miles. Took it back to the dealer where I bought it from and have an extended warranty. They are telling me the extended warranty denied the coverage for Coolant leak, engine replacement

Cylinder head cracked at 100k. There is tsb knowing that this is a problem. It even stats that it happens during Manufacturing there was a defect. Coolant is leaking out the back side of the motor. Causing a over heating conditions stranding my family on the side of the highway.

The 2018 Mazda CX-9 has been experiencing significant engine coolant leaks, which are suspected to stem from a manufacturing defect. The coolant leaks appear to be primarily caused by a casting defect in the engine block or cylinder head, exacerbated by the pressure and heat from the attached turbocharger. These defects lead to coolant escaping from areas that are typically obscured behind the exhaust manifold and turbocharger, making early detection difficult without detailed inspection.

Car started leaking coolant, and running rough / stalling. Eventually overheated due to lack of coolant. Mazda dealer reports Cylinder Head crack as the root cause of the issue. Car has 106K miles - and seems to have the same problem as referenced in NHTSA 10232269 [XXX] ) Mazda has decided to decline to offer any financial assistance in the repair. Replacement cost for just the cylinder head (not a complete engine) was quoted by a Mazda dealership to be $6800 - $7200. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Engine coolant leaks at cylinder heads I started noticing the problem at around 50000 miles its a small coolant leak but car is almost 6 years old and now 54000 miles

I recently bought a Mazda CX-9 and noticed that my vehicle was slightly overheating. The coolant level was very low. I took it back to the dealership I bought it from and they confirmed that there was a crack in the cylinder head and are working on the repair. After further research, I am seeing this is common with these models. Mazda is aware but not taking responsibility.

Cracked Cylinder Head Verified by Mazda Dealer . Noted it seems to be a very common problem with Mazda cx9 2018 models and has Multiple TSB on issue so I kept very close eye on car and took it in as soon as I smelled burning smell suggesting a leak , before the car had the chance to overheat and put myself and kids in danger. My car is under 40k miles for a 2018 with consistent maintenance - this is known problem since 2021 and needs to result in a recall.

Mazda has a known technical service bulletin [XXX] which has numerous engine cylinder heads which leaks coolant causing the engine to overheat without warning. On new cars. Mazda knows it’s an issue and has not pushed this information down to its consumers. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Engine coolant leaking due to cracked cylinder head, found by Mazda dealership service inspection and diagnostics. Powertrain warranty only covers this until 80,000 miles, our vehicle is 116,000.

At 102,000 miles I have a cracked cylinder head

Cracked cylinder head resulting in no heat, leaking coolant and risk of overheating and fire. Crack on backside of cylinder head near exhaust manifold bolts. Weight of exhaust manifold is too much for the cylinder head and results in a Crack around the bolt. Cylinder head was casted too thin at the factory resulting in the head no being able to support the weight of the turbo and exhaust manifold. Mazda is not covering the defect under goodwill when customer is outside of warranty even though it effects every 2.5 turbo engine made between 2015 and 2020.

The contact owns a 2018 Mazda CX-9. The contact stated that while the vehicle was parked, he observed condensation under the vehicle. The vehicle was towed to an independent mechanic where it was diagnosed that the engine needed to be replaced. The vehicle was repaired but the failure persisted. The contact stated that while the vehicle was parked, he observed condensation under the engine compartment and on the top of the engine. The vehicle was taken to an independent mechanic where it was diagnosed that there was a crack in the cylinder head and that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 68,000.

My 2018 Mazda CX-9 developed a rapid overheating issue which was determined to be caused by a cracked cylinder head. This was a known issue by Mazda as noted in a technical service bulletin (Mazda TSB 01-013/21). I've been told by Mazda corporate and the Mazda dealership where the car is currently parked that this bulletin means nothing and will they will not cover the cost of repair. My extended warranty is also telling me that they will not cover the cost of repair because they don't cover damage caused by overheating. Even though The leak caused the overheating in the first place.

Coolant leak in the 3rd cylinder, causing the car to overheat and cracking cylinder head, making inoperable.

We noticed a coolant leak and took vehicle in for service. Told that engine has a Coolant Leak at Cylinder Head [XXX] . 5 year old vehicle, 56k miles. No other warnings. All maintenance has been previously performed as required. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

As I was driving 26 mile trip to work I noticed a red light illuminated on dash indicating the temp was about 240-260. I pulled into the parking lot immediately turned car off. After work (8 hour shift) drove home temp stayed at 200-210. The next morning I took it to the mechanic I’ve used for years. He did a visual detailed inspection finding that the water or antifreeze in the radiator was low. The antifreeze in the over flow tank was about an inch or so above the “L” line. He said there may have been an air pocket in it, a leak, water pump or thermostat going out. Watch the fluid levels daily, if the lower again take it to the dealership where I purchased it (4 months ago with 106K miles on it). I do have a 3 year or 30,000 mile warranty through the dealership. 4...

Went in to the mechanic to get a regular oil change and noticed a liquid slushing sound after starting the car up. Was informed that there is a major coolant leak somewhere in the car. Took it to Mazda dealership right away who confirmed that it is a cracked cylinder head. I got lucky that the car did not overheat on the road and happened to catch it in the nick of time. No check engine lights or low coolant lights came on at all.

Coolant leak not from radiator but from the engine

Car started idling rough and losing power at 135000 miles. Then started to overheat. Mechanic noticed coolant was low and added some. Problem continued to get worse and now engine won’t turn over. Mechanic said it was a cracked head leaking coolant into engine and it’s a known problem with the CX-9.

Just noticed coolant leak during oil change. Vehicle has 77,000 miles. Power train warranty is only to 60K. The vehicle is undriveable without major engine work or engine replacement.

The cylinder head cracked and leaked engine coolant at 72K miles. This is a known design flaw IAW TSB 01-007/22. Vehicle overheated.

Coolant leak from casting defect. Common issue.

The vehicle started leaking coolant, I had it towed to dealer to prevent further damage. They said it has a cracked head, which is a known issue with the 2016-2019 Mazda's, and is acknowledged by Mazda to be their fault. They have posted on a service bulletin that it was caused by added stress during manufacturing. Like many others, they want me to pay over 8k dollars for the repair. This is ridiculous as Mazda has stated that it is their fault.

I noticed my 2018 mazda cx9 Sweet smell coming out of the engine.. When we were driving, a memo came up on my car screen and says please turn off vehicle as soon as possible, overheating. I was Scared That my car could have stopped in the middle of the freeway with my kids in it. My current was low. My engine was really hot and so we took it in to Mazda dealer. They diagnosed my car, and they said it had a cracked cylinder head by the exhaust manifold and because of that, it overheated my engine. This is a manufacturer problem. And it could have harmed my family. Mazda now doesn't wants to help me fix my this car, even when admitting they are fully aware of it. This happening on a freeway would have caused a major accident. There are Technical service bulletin on this case...

Driving on a major highway, when the engine overheating temperature light appeared on the instrument cluster. Seconds later it appeared and felt as if the engine would seize and come to an abrupt halt in the middle of a major highway. Thankfully I was able to quickly find a place with room to pull over, avoiding a potential collision. The engine coolant abruptly leaked/exited from the vehicle. I believe there is a service bulletin (No.- 01-002/23), but still no signs of a Recall being issued in reference to this safety concern.

Started smelling coolant through AC and noticing that temp would momentarily spike to 240 before going back down to 200. My independent mechanic diagnosed it as a coolant leak in the cylinder head related to Mazda Tech Service Bulletin 01-002/23 (https://www.tsbsearch.com/Mazda/01-002-23). Took it to Mazda dealership, they confirmed a coolant leak and wish to replace the whole engine. Problem is that vehicle 1) has 105K miles and is not under warranty 2) Mazda engines are on back order and may not be available until November. I am going through an appeal process with Mazda right now to try to get some relief from a 9K repair bill. Disappointed that this known issue ( several threads in the Mazda forums ) is not getting the attention from Mazda that it deserves.

A coolant leak appeared around 62,000 miles. Car started overheating and come to find that I had no more coolant left in the reservoir. I filled it back up and drove it to the mechanic, after almost a week in the shop and have been quoted over $2k for the fix. There is a TSB out on this issue. It is a known issue apparently from a casting defect in the heads / block.

A coolant leak appeared around 60,000 miles. I caught it in the right time as I had no more coolant left in the reservoir. I filled it back up and drove it to the Mazda dealership - I did not overheat at all so no warning lamps appeared. Upon taking it into the Mazda dealership, the engine was pulled and it was discovered that the cylinder head was cracked. This requires a new engine. There is a TSB out on this issue. It is a known issue apparently from a casting defect in the heads / block.

coolant leaks at the cylinder head around the exhaust manifold , safety was compromised by car overheating in the middle of extremely high level traffic, problem confirmed by Mazda dealership, only inspected by dealership, there was no warning indicators from the vehicle. I could smell antifreeze the day before it overheated.